eval_binary

eval_binary   f   a   b

Evaluates f a b. f can also be an operator.

Source code:

    if { [regexp \[a-z\] $f match] } {
	# Seems that "f" is a function (because the name contains letters).
	eval "$f {$a} {$b}"
    } else {
	# Seems that "f" is an infix operator like "+", "*" or "||".
	expr $a $f $b
    }